1. Field of the Invention
The present invention relates to an axial fan. More particularly, the present invention relates to a blade shape in the axial fan.
2. Description of the Related Art
Most electronic devices generate heat therein and use cooling fans for dissipating the heat. In recent years, the amount of heat has continued to increase with improvement of performance of the electronic devices. The increase in the amount of heat raises a required level of performance of the cooling fans, which in turn requires improvement of flow rate characteristics and static pressure characteristics. Both those characteristics can be improved by rotating the cooling fans at higher speeds. However, because of increasing use of electronic devices in office and at home, demands of reduction in noises during rotation of the cooling fans are increasing.
The size of casings of electronic devices has continued to be reduced in recent years. The reduction in casing size has imposed various limitations on a space for installing a cooling fan. For example, in order to achieve sufficient cooling performance of the cooling fan, an unoccupied space has to be provided in the electronic device next to an air-inlet side of the cooling fan so as for another component or device to disturbing the cooling fan from drawing in air. However, because of the reduction in casing size described above, it is not possible to form the unoccupied space required for drawing-in of sufficient air next to the air-inlet side of the cooling fan.